Electric alarm device



Feb. 9, 1932. F. W MYERS 1,844,331

ELECTRIC .ALARM DEVICE Filed Deo. 8, 192B 2 Sheets-Sheet l WJ i7 Feb. 9, 1932. Ffw, MYERS 1,344,331

ELECTRIC ALARM DEVICE Filed Deo. 8, 1928 2 Sheets-Sheet 2 Patented Feb. 9, 1932 UNITED STATES PATENT FFECE FRANK W. MYERS, OF DENVER, COLORADO, ASSIGNOR TO THE ELECTRIC ALARIII CO., INC, F DENVER, COLORADO, A CORPORATION OF COLORADO ELECTRIC ALARM DEVICE Application led December 8, 1928. Serial No. 324,621.

This invention relates to improvements in electric alarm devices and has reference vmore particularly to an improved theft alarm of the type Vdescribed and claimed in United States application Serial No. 746,171, filed Cctober 24, 1924.

It is often desirable to provide automobiles and buildings with means for sounding an alarm, if they are disturbed or entered by an m unauthorized person, and it is to means for this purpose to which this invention relates.

In Aconnection with automobiles it is desirable toph'ave a signalling device that will become operative if the automobile is disturbed and which will sound the horn or a bell for a predetermined length of time, after each disturbance, and which will automatically become inoperative if the disturbance Y y ceases. grlhis invention, brieliy described, comprises a control switch'yby means of which the signal is operated and which is normally open, a theft protective switch comprising a pendulous member mountedvfor oscillation 2 5 about a pivot and carrying an electrical contact which, when moved against a cooperating contact, closesa circuit which sets the signal-in operation, an electromagnet having a pivoted armature, a time limit cut-off switch in series with an electromagnet and means operated by the armature for interrupting the current that flows through the magnet so as to cause the armature to vibrate and means also operated by the armature for intermittently closing the signal con trol switch.

Having thus briefly described the invention, the same will now be described in detail and for this purpose reference will be had to the accompanying drawings, in which the preferred embodiment of the invention has been illustrated and in which:

Fig. 1 is a top plan view looking into the casing with parts broken away to better show z5 the construction;

Fig. 2 is a section taken on line 22, Fig. 1

Fig. 3 is a section through a portion of the' armature showing the pawl connected thereto;

Fig. 4 is a section taken on line 4-4, Fig.

l, and shows the manner of pivoting the armature to the casing;

Fig. 5 is a section taken on line 5 5, Fig. 1;

Fig. 6 is a section taken on line @-6, Fig. 1;

Fig. 7 is a section taken on line 7 7, Fig. 5; and

Fig. 8 is a diagram showing the relationship of the several elements and the manner in which they are electrically interconnected.

In the drawings reference numeral 1 represents a rectangular casing or housing within which the parts are located and 2 represents 65 a removable cover, while reference numeral 3 indicates the bottom of the boX to which some of the parts are attached. This casing is preferably so constructed that its sides eX- tend beyond one of the end members in the manner indicated by reference numeral 4 and terminate in outwardly extending lugs 5, which are provided with perforationsl 6 for the reception of bolts or screws by means of which the apparatus is secured in place to an automobile body, or to a building or to any other article or structure with which it is to be used. Secured to one of the end members is an electromagnet comprising a coil 7, which is wound about a core 8 in the usual so manner. One end of this core is secured to the end member of the casing by means of an extension 9, which is preferably riveted over the outer surface of the casing and the other end of the core is provided with a pole piece S5 10 that extends to one side and terminates in a pole face 11. An armature 12 of soft iron is secured to a soft iron strap 13, one end of which is provided with two spaced ends 14 that perforated for the reception of cotter pin 15. A U-shaped brace 16 is secured to the side of the casing by means of a rivet 17 and has its arms perforated for the reception of the Cotter pin, which extends through the openings in the parallel arms 95 and through the ends 14 in the manner shown in Fig. 4. The other end of the strap 13 is provided with spaced ends 18 which are perforated for the reception of a pivot pin 19 and between which is pivoted one end of the 100 pawl 20. A spring 21 engages the pawl and tends to rotate it in a counter clockwise direction (Fig. 3). Secured to the armature strap 13 is a. flexible metal strip 22, whose inner end 23 is located between the armature 12 and the strap 13 and is held in position by means of a rivet or screw 24. The metal strip 22 is provided with two arms 25 and 26 which are bent at right angles and which `.are covered by short rubber tubes 27. Secured to the base 3 is a member 28 of liber, hard rubber or any other suit-able insulating material. This member is held in place by means of a screw 29. Secured to the insulating member 28 are L-shaped lugs 30 and 31 to' the outwardly extending arms ot which are secured the resilient switch members 32 and v33 respectively. Member 32 carries an electrical contact point 34 and member 33 a similar contact point 35. Secured to the insulating block 28 are two L-shaped bracket members 36 and 37, the outwardly extending arms of which carry contact points that are located opposite to contacts 34 and 35 and are adapted to be engaged by the latter. The switch member 32 is so biased that contact 34 will normally be in electrical contact with the cooperating Contact member carried by bracket 36, while switch member 33 is so biased that the contact 35 will normally be spaced away from the cooperating contact carried by the bracket 37. The arms oit member 22 projects underneath the free end of the resilient switch member 32, but is normally spaced from the latter so as to provide a lost motion connection the purpose of which will hereinafter appear. Arm 26 extends underneath the resilient switch member 33, which rests on the surface of the rubber tube 27'. It will now be seen that when the armature occupies the position shown in full lines in Fig. 1, that the switch comprising contact member 34 will be closed and the switch comprising contact member will be opened. As the armature moves upwardly in response to the energization of the electromagnet, it approaches the dotted line position and shortly after it starts moving the switch comprising contact 35 will be closed and when the surface of the rubber tube 27 engages the under surface of the resilient switch member 32, the switch comprising contact 34 will be open. The switch comprising contact 35 controls the signal.l while the switch comprising contact 34 i is connected in series with the electromagnet and controls the flow of current through the latter.

Secured to the base 3 is a pivot pin 38 which is secured to the bottom 3 and extends upwardly into the casing. This pin has a reduced cylindrical portion 39 on which is rotatably mounted a composite disk comprising a ratchet wheel 4() which is secured to the upper surface of a dish-shaped. circular member 41 whose periphery, formed by the flange 42, is circular and is provided with a notch or a cut-out 43 in the manner shown in Fig. 1. A spring 44 is secured to bottom 3 by means of a screw 45 and has its tree end engaging the ratchet teeth on the periphery of the ratchet wheel 40. This spring serves as a detent which prevents the ratchet wheel from rotating in a clockwise direction, Fig. 1, but permits it to rotate in a counterclockwise direction. 'The pawl 20 carried by the armature is so located that its end engages the notch of the ratchet wheel and the free end of member 13 is made of such length that when the ratchet wheel has rotated through an angle corresponding to the angular extent of one ofthe ratchet carrying teeth, the end of member 13 will engage the ratchet teeth and serve as a stop in the manner indicated by dotted lines in Fig. 1. Secured to base 3 is an insulating block 46 to which are secured a resilient contact 47 and an L-shaped bracket 48. These two members are held in place by means of a screw 49 and the upwardly extending portion of bracket 38 carries a contact point 50. The free end of the resilient contact 47 is so positioned that it will engage and make electrical contact with the circular periphery of flange 42 except when the parts are so located that its end occupies the position shown in Fig. 1, where it has been indicated as being located in the depression 43. A conductor 51 connects the bracket 48 and the contact 47 with one end of the magnet coil and the other end of this coil is connected by means of a conductor 52 with the bracket 30 and with the switch member 32. Another conductor which has been indicated by reference numeral 53 extends from the bracket 36 to binding post 54. Binding post 54 is connected by means of a conductor 55 to one pole of a battery 56, the other pole of which is grounded at 57. It we consider that the casing 1 is grounded, we will now find that it the ratchet wheel is moved so that the end of spring 47 comes into electrical contact with the surface 42, a complete circuit will be established through the electromagnet which will therefore become energized and attract the armature, thereby stepping the ratchet wheel around through an angular extent corresponding to the angular extent of one tooth. As the armature moves up the switch comprising contact 34 will open and deenergize the magnet, thereby permitting the armature to fall back to the position in full lines and this will be repeated until the notch 43 is brought underneath the end of contact 47 whereupon the circuit will be broken and the operation cease. As the armature reciprocates, the signal control switch will be intermittently closed as above explained.

For the purpose of starting the operation of this mechanism when it is subject-ed to vibrations a theft control switch has been provided. This switch comprises a pendulum member 58 one end of which is pivoted at 59 and the other end of which is provided with an kenlargement 60 of considerable weight. The pendulum 58 is secured to the casing by means of a bracket- 6lwhich is held in place by means of screws 62 and which has its parallel side members connected by means of a screw 63. The side members are provided with depressions for the reception of the conical ends of the pivot pin 59, 7. y means of the screw 63, the pivotal bearing can be adjusted so as to compensate for wear and so as to obtain the best results. The arm 58 of the pendulum has its pivot end bent into U-shape in the manner shown in Fig. 7. Secured to the connecting port-ion 6st of this U-shaped part is a tension spring 65, whose other end is anchored to the upstanding arm 66 of a bell crank lever which is pivoted at 67. The other arm of this bell crank lever is provided with an offset portion 68 that is engaged by the inner end of the adjusting screw 69, which is held in adjusted sition by means of a lock nut 70 and which serves to regulate the tension in sprinn 65. A contact 7l is carried by the pendulum so located that it will engage the contact 56 when the pendulum moves a short distance towards this Contact. A spring' 72 is secured to the casing and rests against the inner surface of the weight 66 and exerts a yielding force tending to move the pendulum so as to keep contacts 50 and 7l separated. A. steel plate 73 is secured to the outer surface of the weight 60 and this engages the inner pointed end of the adjustingl screw 74 which is held in adjusted position by means of a lock nut 75. By properly adjusting the screw 74, the gap between the contacts 50 and 7l can be adjusted so as to get the most desirable results. t is apparent that when contact 71 is moved against contact 50, that the electric currentpasses from the conductor 5l to the contact 50 and thence to contact 7l, which is connect-ed with the ground and energizes the magnet, thereby attracting the armature and moving the ratchet wheel so as'to bring the free end of contact i7 in electrical cont-act with the surface 42. In other words, the theft protective switch comprising contacts 7l and 50 is in shunt with the time limit switch comprising the rotatable dist and the spring 47. After the parts have been set in motion by the operation of the theft protective switch, they continue to operate until. the ratchet wheel has rotated three hundred sixty degrees, when the parts automatically stop. lt is, of course, apparent that the contact surface l2 may be provided with as many depressions i3 as may be desired, so that it is not always necessary 'that the ratchet wheel shall rotate three hundred sixty degrees, as the rotation will stop whenever a depression 43 comes underneath the end of contact 47 and by this simple expedient the ratchet wheel may be made to rotate any fraction of a complete revolution.

ln Fig. 8 the parts have been shown diarammatically and the signal which is to e operated has been indicated as a horn which has been designated by reference numeral 76, one terminal of this horn has been indicated as grounded at 7 7 while the other terminal is connected by means of a conductor 78 to the binding post 79 from which conductor 8O extends to the bracket 8l. A conductor 81 entends from the bracket 37 to binding post 82 and the latter is preferably connected with binding post 54 by means of a conductor 83.

With the parts connected in the manner shown in Fig. 8, we will assume that the device is vibrated until contact 7l makes electrical connection with contact 50, a current will then liow from the battery through the electromagnet control switch, thence through the electromagnet and through conductor 51 to contact 50, thence to Contact 7l and to ground. The electromagnet will now be energized and attract the armature l2, thereby closing the signal control switch and opening the electromagnet control switch and at the same time rotating the ratchet wheel to the eXtent of the width of one tooth. rlhis brings the end of contact l-7 ont-o the surface 4t2 and grounds the Contact 47 through the ratchet wheel. The electromagnet will now continue to be periodically energized until notch 48 again occupies a position underneath the end of spring e7 when the parts will stop. During this time the signal control switch has operated intermittently and caused the signal to be sounded. If the disturbance is not repeated the parts will remain in inoperative position, but if the disturbance is repeated. the signal will continue to operate until the parts are brought to rest. A con denser 84is connected across the contacts of the electromagnetic control switch so as to prevent undue sparking.

The adjustment effected by means of screw 7 4 is very important as it is independent of temperature variations and therefore the adjustment can be maintained very accurate at all times and the contacts spaced so as to get the most desirable results. By means of the screw 63, the bearing of the pendulum can be adjusted so as to keep this in the best condition for successful operation.

The device above described is well suited to be attached to an automobile and can then be employed for sounding the horn with which the automobile is equipped or it may be attached to house so that it will be set in operation by vibrations caused by some one walking over the floor or it may be connected with doors and windows in such a way that whenever the latter are disturbed the time limit control switch will be short circuited so as to set the mechanism in motion.

It is therefore obvious that this is a device suitable for general application as a burglar alarm, but is especially well adapted as above stated for use on automobiles as it will re- "spond to any disturbance of the car and will therefore act as a theft protective device for spare tires, tools and every accessory without making it necessary to provide special switches and special connections to each one of the devices to be protected.

Having described the invention what is claimed as new is.

A normally open theft protective switch comprising, in combination, a casing having a bottom and side walls, a bracket secured to the inner surface of a side wall, a substantially rigid switch arm having one yend pivoted to the bracket, said arm extending substantially parallel with one side of the casing, a weight secured to the free end of the arm, an adjustable stop carried by one side of the casing, a tension spring having one end connected with the switch arm at a point spaced from its pivotal connection with the bracket, a bell crank lever pivoted at its een ter point to the casing, the other end of the spring being connected with one end of the bell crank lever, means for turning the bell crank lever about its pivot for the purpose of adjusting the tension of the spring, a stop f carried by the casing for limiting the moveist ment of the arm in response to the action of the spring, a switch contact carried by the casing and insulated therefrom, a contact can ried by the switch arm and adapted to come into electrical Contact with the contact carried by the casing when the switch arni moves away from the stop.

In testimony whereof I aiiix my Signature.

FRANK w. MYERS. 

